動機

照題目做

Problem

Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:

  1. Each row must contain the digits 1-9 without repetition.
  2. Each column must contain the digits 1-9 without repetition.
  3. Each of the nine 3 x 3 sub-boxes of the grid must contain the digits 1-9 without repetition.

Note:

  • A Sudoku board (partially filled) could be valid but is not necessarily solvable.
  • Only the filled cells need to be validated according to the mentioned rules.

 

Example 1:

Input: board = [[5,3,.,.,7,.,.,.,.],[6,.,.,1,9,5,.,.,.],[.,9,8,.,.,.,.,6,.],[8,.,.,.,6,.,.,.,3],[4,.,.,8,.,3,.,.,1],[7,.,.,.,2,.,.,.,6],[.,6,.,.,.,.,2,8,.],[.,.,.,4,1,9,.,.,5],[.,.,.,.,8,.,.,7,9]]Output: true

Example 2:

Input: board = [[8,3,.,.,7,.,.,.,.],[6,.,.,1,9,5,.,.,.],[.,9,8,.,.,.,.,6,.],[8,.,.,.,6,.,.,.,3],[4,.,.,8,.,3,.,.,1],[7,.,.,.,2,.,.,.,6],[.,6,.,.,.,.,2,8,.],[.,.,.,4,1,9,.,.,5],[.,.,.,.,8,.,.,7,9]]Output: falseExplanation: Same as Example 1, except with the 5 in the top left corner being modified to 8. Since there are two 8's in the top left 3x3 sub-box, it is invalid.

 

Constraints:

  • board.length == 9
  • board[i].length == 9
  • board[i][j] is a digit or '.'.

Sol

def h(b,i,j):
    hi2 = Counter([int(b[x][j]) for x in range(len(b)) if b[x][j] != "."])
    #print(hi2,i,j)
    for n in range(1,10):
        n = int(n)
        #print(hi2.get(n,0))
        if hi2.get(n,0) > 1:
            return False
    return True
def f(b,i,j):
    hi = Counter([int(b[i][x]) for x in range(len(b)) if b[i][x] != "."])
    
    for n in range(1,10):
        n = int(n)
        if hi.get(n,0) > 1:
            return False
    return True
def g(b,i,j):
    hi = set()
    for a in range(i,i+3):
        for bb in range(j,j+3):
            if b[a][bb] != ".":
                if b[a][bb] not in hi:
                    hi.add(b[a][bb])
                else:
                    return True
    return False
class Solution:
    def isValidSudoku(self, b: List[List[str]]) -> bool:
        for i in range(0,9,3):
            for j in range(0,9,3):
                if g(b,i,j):
                    return False
        return all([h(b,0,j) for j in range(len(b))]) and all([f(b,i,0) for i in range(len(b))])